GEOLOGIC COMPLEXES OF THE SOUTHERN MARGINAL PART OF THE SIBERIAN CRATON AS INDICATORS OF THE NEOPROTEROZOIC SUPERCONTINENT EVOLUTION

Abstract

The aim of this paper is to discuss the Late Precambrian rock complexes in the southern margin of the Siberian Craton, associated with the extension. The analysis of the data available suggests two episodes of intracontinental breakup which resulted in the opening of oceanic spaces (1300-900 and 850-550 million years). The time sequence of "volcanogenic terrigenous rocks of rifting origin → basic dike swarms → carbonate-terrigenous rock sequences → ophiolites and island-arc rocks'''' reflects the consecutive change of geodynamic environments in the marginal part of the craton. The stage of intracontinental rifting was replaced by the stage of advanced rifting, which preceded the continental breakup and the formation of the oceanic crust. Next followed two stages of oceanic crust evolution: the passive stage (sedimentary complexes of the passive margins) and the active stage (island arcs, backarc seas, and the like). Different versions are discussed for the manifestation of extension processes in the southwestern and southeastern segments of the Siberian Craton in connection with the breakup of the Rodinia supercontinent.